1. Field of the Invention
The present invention relates to a liquid crystal display device provided with pigmented layers in a pixel thereof.
2. Description of the Related Art
In recent years, liquid crystal display devices have been widely utilized in various appliances such as a mobile phone and a notebook computer. A liquid crystal display device includes a display unit provided with a pixel in each of intersections determined by a plurality of scanning lines and a plurality of signal lines, and a driver which drives the scanning lines and the signal lines. Each of the pixels further includes a thin-film transistor (TFT), a liquid crystal capacitor, and an auxiliary capacitor. The display unit is formed on an array substrate made of glass. Additionally, in consequence of development of manufacturing process technologies, it has become possible to form a part of the driver on the array substrate, and thus, weight reduction, slimming down, and miniaturization of an entirety of the liquid crystal display have been pursued.
On a display area in a liquid crystal display device, as shown in a plan view in FIG. 1, a first pigmented layer 11, a second pigmented layer 12, and a third pigmented layer 13 are provided. For example, the first pigmented layer 11, the second pigmented layer 12, and the third pigmented layer 13 are pigmented in green, blue, and red, respectively. One pixel is formed of three portions which are of these pigmented layers 11 to 13, respectively. The first pigmented layer 11 is formed in a pattern of vertically aligned stripes alternately repeated, as shown in FIG. 1. Alternatively, as shown in a plan view of FIG. 2, the first pigmented layer 11 is formed in a grid pattern enclosing portions of the second and third pigmented layers 12 and 13.
Nevertheless, in both of the cases where the first pigmented layer 11 is formed in the stripes and where it is formed in the grid pattern, when the array substrate is coated with the second pigmented layer 12, uneven coating attributable to the pattern of the first pigmented layer 11 is more likely to occur with increasing microminiaturization of the array substrate.
Causes of the uneven coating are as follows. In the case where the first pigmented layer 11 is formed in the stripes, when the array substrate is coated with the second pigmented layer 12 by using a spin-coating method (spin-coater method) in a second process following a first process where the first pigmented layer 11 is formed, the color resist of the second pigmented layer flows along borders of the first pigmented layers by receiving centrifugal force, the color resist still having fluidity before its hardening.
In the case where the first pigmented layer 11 is formed in the grid pattern, when the array substrate is coated with the second pigmented layers 12, resistance in a direction of preventing the second pigmented layer 12 from spreading out in a direction of the centrifugal force becomes larger with increasing density of the grid pattern. As a result, for example, uneven coating occurs in a particular direction such as a diagonal direction of the grid pattern.
Accordingly, conventionally, for the purpose of preventing occurrence of uneven coating with the pigmented layers in association with the spin-coating method, the followings have been performed. Specifically, as shown in a plan view in FIG. 3, there has been used a pattern obtained by thinning out a portion from the grid pattern of the first pigmented layer 11 shown in FIG. 2 every other pixel in a vertical direction (a signal line direction), the portion corresponding to the second and third pigmented layers 12 and 13 in a lateral direction (a scanning line direction). On a region where the portion of the first pigmented layer 11 is thus thinned out, each of the second and third pigment layers 12 and 13 is formed in a place which is originally a break for the each.
However, in the pattern in FIG. 3, when a lateral arrangement of the pigmented layers is brought into focus, there are lines of two kinds alternatively arranged. The two kinds are one kind simply including the respective pigmented layers 11 to 13 alternately continuing in a lateral direction, and the other kind including, in addition to a region where the respective pigmented layers 11 to 13 alternately continue in a lateral direction, a region where the first pigmented layer 11 continues in a lateral direction.
In this configuration, among the lines, an area of the first pigmented layer 11 is different every other line, and hence a light reflection ratio is different every other line. As a result, line defects extending in a lateral direction are observed on a display screen, and there arises a problem that they lead to a reduction in display quality.